Stephanie P.
Yelp
This was our first stop from Tokyo on a day trip to Hakone, partly because a travel guide suggested you only needed about 30 minutes at Odawara Castle. While that may be true, it doesn't take into account the walk to and from the station or the stuff you might want to see around Hakone that also closes early, so read on to see if you should visit!
Odawara station is about 30-40 minutes from Tokyo station, and the trip is free with your JR rail pass, making it a good quick excursion if you have a couple of hours to kill. You can buy either a ticket just to the castle (about 500 yen), a combined ticket including the Spirits of the Samurai exhibit (600 yen), or a ticket including the castle, the samurai gallery, and a local history museum (700 yen). I'd suggest the castle & gallery option, but 100 yen is pretty cheap if you think you might want to check out the small museum on the grounds (we didn't).
Prepare yourself for STAIRS. There's a steep stone stairway just to get to the castle entrance, and from there you'll climb four more sets of stairs to get to the rooftop view payoff. They try to sweeten the deal by including historical exhibits along the way, but man, that is a lot of stairs. The view at the top is pretty great, though, and you can walk all around the balcony for some excellent pictures. I didn't see any elevators, so this is probably not suitable for anyone who can't handle a significant amount of fairly steep and sometimes irregular stairs, especially in bad weather.
We were surprised at how modern the inside was. I think we were both expecting something more like Nijo-jo, with wooden floors and painted screens and tatami mats. Nope. The interior is brightly lit, painted white, with carpeted floors, which was a little disappointing. They explain in the adjoining samurai gallery that when they retrofitted the castle against earthquakes during a remodel, it ate up some of the museum display space, which is why the samurai armor and swords were moved into a separate outbuilding. They should probably just charge one flat fee for both, but you should definitely pay the extra 100 yen to check out five full suits of armor, a cool animated video, and some swords and accessories of the samurai lifestyle.
Is it English-friendly? Sort of. Some effort was made to include signage and explanations in English, at least for the main overview signs and bigger displays, but most of the artifacts, videos, etc., are presented with Japanese-only descriptions. It's still enjoyable to look at the swords, pottery, roof tiles, and so on, but don't expect full English-language signage.
Outside the castle, there's the previously mentioned samurai gallery, a snack shack, and a gift shop that includes a dress-up costume rental if you want to release your inner samurai. They have kid and adult sizes available, though the costumes looked a little lower in quality than, say, the kimono rental shops in Kyoto. If you have a dream of kimono dress-up and you're going to Kyoto, I'd say wait for that instead.
Overall, a fun side trip as part of our day trip to Hakone. If I were to do it again, I'd get an earlier start out of Tokyo (because so many things in Hakone close early) and do Odawara on the way back, allowing about an hour of castle time. But if this is your one chance to check out a castle, Odawara is an easy and accessible half-day trip from Tokyo.